Creosote in the present disclosure is intended to mean deposits of any kind that form in heating devices and particularly in chimney flues. These deposits are typically particles of carbonaceous materials, flying ash or chiefly tars. The latter settle mainly in the lower portion of the flue ducts or chimneys. Formation and settling of these materials are dramatically increased when burning sold fuels such as coal and wood, particularly when using air-tight stoves.
The increased settling of these materials, especially tars, in chimneys is dangerous since these materials are flammable and can be responsible for fires in chimneys. They are also responsible for a decreased draft in chimneys and combustion devices since they decrease the flue section. Conventional sweeping with a flue brush is not effective with tars, which form a hard layer strongly adhered to the walls, so that even after mechanical sweeping a fire in the chimney can still occur.
Materials for the so-called chemical or catalytic cleaning of chimneys are replete on the market. Some of these contain sulfur whose purpose is to decompose soot and tars to make them more flammable. However, because the flue must be heated to a maximum to make the material operative, use of such products creates risks such as a fire in the chimney or damage to the flue through use of caustic soda or decomposition products thereof.
The scientific literature and patents disclose many other chemical or catalytic agents intended to inhibit the settling of deposits in furnaces and chimneys or even to disaggregate these deposits once formed; these agents unhappily cannot be handled easily in many cases, particularly when present as a liquid or a powder. The liquid agents require injection nozzles and their use is not feasible with domestic heating devices; the powdered agents cannot be used easily since a powder in more or less precise dosage must be sprinkled onto a fire of variable intensity, whose measure and control cannot be carried out easily.
Finally a large portion of the powder or decomposition products is lost in the atmosphere, which results in economic losses and pollution hazards.
Manufactured logs for domestic use have not been entirely satisfactory either in burn characteristics or in costs. The main advantages of processed fire logs generally include long burn time, easy lighting characteristics, and convenience of use for preparation or maintenance of a fire. As a replacement to natural wood fires, processed logs offer the convenience of not having to stoke the fire to ensure a consistent flame. One log typically burns for 2 to 4 hours, depending on the size of log. However, these advantages are not unqualified. In order to achieve both a substantial flame and a quick ignition time, a significant amount of wax has been used. The high combustion rate in combination with a limited air supply available in most modern houses typically results in incomplete combustion, which in turn leads to a buildup of soot and creosote in the flue. Repeated use of such fire logs can thus create a fire hazard. In fact, due to the seriousness of this problem, insurance companies recommend that consumers alternate between the use of processed fire logs and natural wood fires, in addition to frequent cleaning of combustion apparatus.
Not only does the excessive use of wax represent a safety hazard due to the build-up of soot, it also means that the consumer is provided with an aesthetically less pleasing product as compared to natural wood fires. While the substantial use of wax promotes faster ignition, the flame height for the later stages of combustion is significantly lower than when a fire log is first lit. Consequently, it is difficult for a user to enjoy a flame comparable to a well-maintained natural wood fire.
A further disadvantage of fire logs high in wax content is the pollution produced during combustion. The volatility of wax causes a fast, sooty initial burn that ejects copious amounts of combustion by-products including soot and carbon monoxide that is released into the atmosphere. In addition, some prior art manufactured fire log compositions contain substances which are toxic or potentially toxic when combusted. Thus, there exists a need for a safe, clean burning fire log that maintains good flame consistency over an extended period of time.
A further disadvantage of fire logs high in wax content is that their use can void the warranty of the wood burning appliance. Also, according to published data, fire logs high in wax content are intended to be burned in fireplaces only.
FR-A-2 554 458 discloses a solid combustible agent for preventing or curing soot in heat generating devices. The agent comprises e.g., wood particles, a soot preventing or curing agent and a binder. The agent is used in an active conventional fire in low proportion, e.g. a few tens of grams of active material per each metric ton of fuel.
The use of wax as a binder for sawdust in artificial logs is known from U.S. Pat. No. 4,147,518, 3,297,419 and 3,637,355. Chemicals in minor proportions may be added to improve the combustion or produce colored flames, but the resulting logs do not appear to have any effect on soot or tars in chimney flues.
U.S. Pat. No. 5,882,365 discloses a soot disaggregating combustible agent comprising an aggregate of cellulosic particulate material, chemical and/or catalytic soot disaggregating agent and a binder.
GB-A-2 145 731 discloses cellulose briquettes incorporating combustion modifiers such as sulfur oxyacid derivatives or phosphorus oxyacid derivatives.
GB-A-1 001 772 discloses a cleaning agent for heat transfer surfaces which comprises a mixture of potassium nitrate and a combustible material. This agent is introduced into a hot furnace.
U.S. Pat. No. 4,481,010 discloses a creosote and soot removing composition comprising a metallic chloride and trisodium phosphate, said composition being sprinkled onto a fire.
U.S. Pat. No. 2,777,761 discloses a composition comprising ammonium chloride, copper sulfate and wood flour that assists in the burning of soot and carbon deposits in combustion chambers, flues, etc.
WO-A-82 04065 discloses a process for removing soot from enclosed spaces comprising the introduction of steam saturated with specific chemicals.
U.S. Pat. No. 5,284,636 discloses the use of phosphorous oxide to stabilize the ash produced by the combustion of a heavy metals containing fuel.
DE-A-3 429 584 discloses a combustion improving composition comprising a number of chemicals including ammonium compounds which are said to clean heating devices and flues.
While a number of soot inhibiting or soot removing (disaggregating) agents have been disclosed, it appears that none of them has been used in the same composition or in the same manner as in the present invention.
The disadvantages of the cleaning agents of the prior art are largely overcome by the use of a solid cleaning agent for disaggregating soot according to the present invention, particularly the use of the preferred embodiment of this agent.